The problems encountered in cutting both crimped and uncrimped fibers in tow or ropelike feed are well known in the textile industry. Uniformity of length is particularly difficult to achieve in staple cut from crimped tows. Thus overlength staple is produced, resulting in extreme difficulty in subsequent processing in the drawing machinery.
Fusing of ends is an additional problem on all cutters, particularly where impact of the blades and the cutting force combine to produce local heat which is near the melting point of the material being processed. Wetting down of the tow or rope is employed in many instances to dissipate heat of fusion, but it is an unsatisfactory alternative since it necessitates subsequent drying, hence expensive and unnecessary equipment and added cost to the product. Even wet end usage results in inflated handling, packaging and transportation costs.
Feed is also a problem in most cutters, particularly those of the knife and anvil and Beria types. Vacuum is in common use to direct the tow band from the final feed rollers to the knife, anvil pinch point. While this method produces staple, two problems are inherent in its use: folds or length variation irregularities in the tow are immediately stretched out by the suction, thus producing long ends. Also, equipment must be supplied both to produce the vacuum and to separate cut staple from the air stream at some point downstream from the cutter. The separation problem is particularly troublesome on short flock-like staple. While vacuum is not in common use on the Beria type cutters, centrifugal force stretches out the irregularities in the tow band and produces the selfsame objectionable long ends.
An apparatus overcoming the aforementioned difficulties has been proposed by this inventor and is the subject of an U.S. Pat. No. 3,768,355 entitled "Method and Apparatus for Cutting Fibrous Tow into Staple." This apparatus involves a power operated rotatable hollow shaft, having an inlet and an outlet passage for tow or rope. Adjacent to the outlet passage is a frame having a plurality of knives radially positioned with their sharp edges closely adjacent to the outlet passage. Movement of the tow or rope through the passageway impinges the outer side of the tow or rope against the sharp edges to cut the tow or rope in fibers of generally very uniform length. The knives are mounted to be adjustable with respect to the outlet passage whereby to continuously present a sharp portion of the knife edge for cutting purposes.
This latest improvement to the art of cutting tow or rope does not completely meet the demands of the industry in that the apparatus has somewhat limited production capabilities since, particularly at higher rates of throughput, the apparatus involved generation of excessive heat created by the frictional sliding contact of the tow on the cam surfaces.
An object of the instant invention is to provide a satisfactory resolution to the aforestated problems.
Another object of the instant invention is to provide a means to simultaneously feed a plurality of tows to a cam operated rotary staple cutter.
A further object of the invention is to provide a means whereby frictional heating generated between the tow and the cam surfaces is eliminated.
It is a further object of the present invention to provide a cooling means for the machinery which utilizes a liquid which may be mixed with the cut staple to provide a desired end product, complete with required finish.
It is a still further object of the present invention to provide a tow cutting apparatus which is relatively inexpensive to produce and operate and is relatively maintenance free and provides consistent uniform results.
An additional object of the present invention is to provide a tow cutting apparatus which will impart any desired magnitude of twist to the tow feed, regardless of inlet feed speed, thereby making it possible to satisfactorily cut a variety of fibrous materials considered to be unprocessable previously.